The Federal Motor Vehicle Safety Standard No. 208 (FMVSS208) is a safety standard issued by the National Highway Traffic Safety Administration to measure how well a passenger vehicle would protect its occupant in the event of a frontal load event (such as a frontal crash). To meet the driver federal FMVSS208 test requirements and to meet public domain corporate objectives for occupant safety, it is essential to provide and maintain an effective steering column energy management system.
When a forwardly directed impact load is imposed upon the steering wheel, one of the functions of the steering column is to dissipate the energy of an impact load directed against the steering wheel. Installation of an energy-absorbing steering column decreases rearward displacement. If a steering column absorbs the impact, it lessens the severity of driver injuries. A typical steering column assembly includes an intermediate shaft that is connected to a steering wheel at one end and a steering gear assembly at the opposite end. During a load event (such as a frontal impact), the steering column is pushed downward in response to a force from the load event. Sometimes, due to a limited length of the intermediate shaft, an impulse load is transmitted back (rearward) through the steering column and back to the steering wheel. The steering wheel may be pushed towards the driver upon impact, transmitting excessive force into the driver's head and\or chest.
Existing solutions include a decoupling (breakaway) intermediate shaft that is implemented to overcome these issues. More specifically, upon encountering a load event, a lower portion of the intermediate shaft decouples from an upper portion of the intermediate shaft, thereby preventing the upper portion of the intermediate shaft from bottoming out and sending a rearward impulse force back through the steering column. With the upper portion (connected to the steering wheel) decoupled from the lower portion (connected to the steering gear assembly), the driver is no longer capable of controlling the vehicle with the steering wheel. This is a problem if the lower shaft decouples from the upper shaft during a mild load event, such as during normal or off road driving conditions.
Accordingly, there is a need for a solution to these problems. This invention disclosure attempts to overcome the concerns of the “standard” original decoupling design with an enhanced concept.